The car's driver Dean Jonathan McCartney, 21, and passengers Jethro Bronson Cooper, 16, and Kodee Marie Rapana, 15, died in the crash.
Redeemed's lawyer Lee Lee Heah argued against his conviction and sentence in the Court of Appeal today.
She asked the court to admit new evidence from AUT mechanical engineering expert Professor John Raine, who agreed with the Crown that the crash was caused by the car's wheel being turned.
But Dr Raine's crash analysis differed on the key point that the wheel could have been turned either deliberately or inadvertently.
The trial was told there had been "fooling or skylarking" in the car which caused it to veer over the centre-line in the minutes before the fatal crash.
But Ms Heah said evidence the crash could have been caused inadvertently as a result of the tomfoolery was never properly put to the jury.
"There was no credible alternative explanation."
Instead, Redeemed's defence strategy at trial was to question the credibility of key witness Reece Dick-Durham, who was the only passenger in the car besides Redeemed to have survived the crash.
Mr Dick-Durham told the jury he saw Redeemed look at the bus before grabbing the wheel.
But Ms Heah said there was no way Mr Dick-Durham could have seen where Redeemed was looking from the back seat of the car.
Ms Heah also challenged the admissibility of evidence about a previous incident in which Redeemed grabbed the wheel of a car, after which he said something like: "I could end it."
She said the evidence was highly prejudicial and the trial judge did not properly direct the jury about what weight to give it when he summed up the case.
Ms Heah also appealed Redeemed's lengthy sentence, which included a minimum non-parole period of seven years.
She said previous lengthy sentences were handed down in manslaughter cases where the offender had been driving dangerously over an extended period of time.
But Redeemed's case concerned a momentary action with little forethought of the consequences.
"There has never been a case like this before - it sits in a category of its own."
She questioned whether the uniqueness of the case warranted such a high starting point in sentencing.
Crown lawyer Madeleine Laracy argued Dr Raine's evidence was of limited value and was not admissible.
Even if it was given at trial, the jury would have got the impression that Dr Raine's evidence was in line with that given by the police witness.
"In substance there is no clear difference between them."
Ms Laracy said the evidence on the previous incident was admissible because it showed Redeemed had a tendency to physically interfere with steering wheels, and the judge had summed it up to the jury properly.
She said the 14 year sentence was appropriate, given that the offending was close to murder in seriousness and a life sentence was a possibility.
Justices Terence Arnold, Ellen France and Christine French reserved their decision.
